WM_ACTIVATEAPP message

Sent when a window belonging to a different application than the active window is about to be activated. The message is sent to the application whose window is being activated and to the application whose window is being deactivated.

A window receives this message through its WindowProc function.

#define WM_ACTIVATEAPP                  0x001C

Parameters

wParam

Indicates whether the window is being activated or deactivated. This parameter is TRUE if the window is being activated; it is FALSE if the window is being deactivated.

lParam

The thread identifier. If the wParam parameter is TRUE, lParam is the identifier of the thread that owns the window being deactivated. If wParam is FALSE, lParam is the identifier of the thread that owns the window being activated.

Return value

Type: LRESULT

If an application processes this message, it should return zero.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Winuser.h (include Windows.h)

See also

Reference

WM_ACTIVATE

Conceptual

Windows